diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | include/qapi/error.h | 2 | ||||
| -rw-r--r-- | scripts/coccinelle/errp-guard.cocci | 336 |
3 files changed, 339 insertions, 0 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index f01284ebce..6aa54f7f8f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2176,6 +2176,7 @@ F: scripts/coccinelle/error-use-after-free.cocci F: scripts/coccinelle/error_propagate_null.cocci F: scripts/coccinelle/remove_local_err.cocci F: scripts/coccinelle/use-error_fatal.cocci +F: scripts/coccinelle/errp-guard.cocci GDB stub M: Alex Bennée <alex.bennee@linaro.org> diff --git a/include/qapi/error.h b/include/qapi/error.h index 85df875a3a..7932594dce 100644 --- a/include/qapi/error.h +++ b/include/qapi/error.h @@ -265,6 +265,8 @@ * } * ... * } + * + * For mass-conversion, use scripts/coccinelle/errp-guard.cocci. */ #ifndef ERROR_H diff --git a/scripts/coccinelle/errp-guard.cocci b/scripts/coccinelle/errp-guard.cocci new file mode 100644 index 0000000000..6e789acf2d --- /dev/null +++ b/scripts/coccinelle/errp-guard.cocci @@ -0,0 +1,336 @@ +// Use ERRP_GUARD() (see include/qapi/error.h) +// +// Copyright (c) 2020 Virtuozzo International GmbH. +// +// This program is free software; you can redistribute it and/or +// modify it under the terms of the GNU General Public License as +// published by the Free Software Foundation; either version 2 of the +// License, or (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see +// <http://www.gnu.org/licenses/>. +// +// Usage example: +// spatch --sp-file scripts/coccinelle/errp-guard.cocci \ +// --macro-file scripts/cocci-macro-file.h --in-place \ +// --no-show-diff --max-width 80 FILES... +// +// Note: --max-width 80 is needed because coccinelle default is less +// than 80, and without this parameter coccinelle may reindent some +// lines which fit into 80 characters but not to coccinelle default, +// which in turn produces extra patch hunks for no reason. + +// Switch unusual Error ** parameter names to errp +// (this is necessary to use ERRP_GUARD). +// +// Disable optional_qualifier to skip functions with +// "Error *const *errp" parameter. +// +// Skip functions with "assert(_errp && *_errp)" statement, because +// that signals unusual semantics, and the parameter name may well +// serve a purpose. (like nbd_iter_channel_error()). +// +// Skip util/error.c to not touch, for example, error_propagate() and +// error_propagate_prepend(). +@ depends on !(file in "util/error.c") disable optional_qualifier@ +identifier fn; +identifier _errp != errp; +@@ + + fn(..., +- Error **_errp ++ Error **errp + ,...) + { +( + ... when != assert(_errp && *_errp) +& + <... +- _errp ++ errp + ...> +) + } + +// Add invocation of ERRP_GUARD() to errp-functions where // necessary +// +// Note, that without "when any" the final "..." does not mach +// something matched by previous pattern, i.e. the rule will not match +// double error_prepend in control flow like in +// vfio_set_irq_signaling(). +// +// Note, "exists" says that we want apply rule even if it does not +// match on all possible control flows (otherwise, it will not match +// standard pattern when error_propagate() call is in if branch). +@ disable optional_qualifier exists@ +identifier fn, local_err; +symbol errp; +@@ + + fn(..., Error **errp, ...) + { ++ ERRP_GUARD(); + ... when != ERRP_GUARD(); +( +( + error_append_hint(errp, ...); +| + error_prepend(errp, ...); +| + error_vprepend(errp, ...); +) + ... when any +| + Error *local_err = NULL; + ... +( + error_propagate_prepend(errp, local_err, ...); +| + error_propagate(errp, local_err); +) + ... +) + } + +// Warn when several Error * definitions are in the control flow. +// This rule is not chained to rule1 and less restrictive, to cover more +// functions to warn (even those we are not going to convert). +// +// Note, that even with one (or zero) Error * definition in the each +// control flow we may have several (in total) Error * definitions in +// the function. This case deserves attention too, but I don't see +// simple way to match with help of coccinelle. +@check1 disable optional_qualifier exists@ +identifier fn, _errp, local_err, local_err2; +position p1, p2; +@@ + + fn(..., Error **_errp, ...) + { + ... + Error *local_err = NULL;@p1 + ... when any + Error *local_err2 = NULL;@p2 + ... when any + } + +@ script:python @ +fn << check1.fn; +p1 << check1.p1; +p2 << check1.p2; +@@ + +print('Warning: function {} has several definitions of ' + 'Error * local variable: at {}:{} and then at {}:{}'.format( + fn, p1[0].file, p1[0].line, p2[0].file, p2[0].line)) + +// Warn when several propagations are in the control flow. +@check2 disable optional_qualifier exists@ +identifier fn, _errp; +position p1, p2; +@@ + + fn(..., Error **_errp, ...) + { + ... +( + error_propagate_prepend(_errp, ...);@p1 +| + error_propagate(_errp, ...);@p1 +) + ... +( + error_propagate_prepend(_errp, ...);@p2 +| + error_propagate(_errp, ...);@p2 +) + ... when any + } + +@ script:python @ +fn << check2.fn; +p1 << check2.p1; +p2 << check2.p2; +@@ + +print('Warning: function {} propagates to errp several times in ' + 'one control flow: at {}:{} and then at {}:{}'.format( + fn, p1[0].file, p1[0].line, p2[0].file, p2[0].line)) + +// Match functions with propagation of local error to errp. +// We want to refer these functions in several following rules, but I +// don't know a proper way to inherit a function, not just its name +// (to not match another functions with same name in following rules). +// Not-proper way is as follows: rename errp parameter in functions +// header and match it in following rules. Rename it back after all +// transformations. +// +// The common case is a single definition of local_err with at most one +// error_propagate_prepend() or error_propagate() on each control-flow +// path. Functions with multiple definitions or propagates we want to +// examine manually. Rules check1 and check2 emit warnings to guide us +// to them. +// +// Note that we match not only this "common case", but any function, +// which has the "common case" on at least one control-flow path. +@rule1 disable optional_qualifier exists@ +identifier fn, local_err; +symbol errp; +@@ + + fn(..., Error ** +- errp ++ ____ + , ...) + { + ... + Error *local_err = NULL; + ... +( + error_propagate_prepend(errp, local_err, ...); +| + error_propagate(errp, local_err); +) + ... + } + +// Convert special case with goto separately. +// I tried merging this into the following rule the obvious way, but +// it made Coccinelle hang on block.c +// +// Note interesting thing: if we don't do it here, and try to fixup +// "out: }" things later after all transformations (the rule will be +// the same, just without error_propagate() call), coccinelle fails to +// match this "out: }". +@ disable optional_qualifier@ +identifier rule1.fn, rule1.local_err, out; +symbol errp; +@@ + + fn(..., Error ** ____, ...) + { + <... +- goto out; ++ return; + ...> +- out: +- error_propagate(errp, local_err); + } + +// Convert most of local_err related stuff. +// +// Note, that we inherit rule1.fn and rule1.local_err names, not +// objects themselves. We may match something not related to the +// pattern matched by rule1. For example, local_err may be defined with +// the same name in different blocks inside one function, and in one +// block follow the propagation pattern and in other block doesn't. +// +// Note also that errp-cleaning functions +// error_free_errp +// error_report_errp +// error_reportf_errp +// warn_report_errp +// warn_reportf_errp +// are not yet implemented. They must call corresponding Error* - +// freeing function and then set *errp to NULL, to avoid further +// propagation to original errp (consider ERRP_GUARD in use). +// For example, error_free_errp may look like this: +// +// void error_free_errp(Error **errp) +// { +// error_free(*errp); +// *errp = NULL; +// } +@ disable optional_qualifier exists@ +identifier rule1.fn, rule1.local_err; +expression list args; +symbol errp; +@@ + + fn(..., Error ** ____, ...) + { + <... +( +- Error *local_err = NULL; +| + +// Convert error clearing functions +( +- error_free(local_err); ++ error_free_errp(errp); +| +- error_report_err(local_err); ++ error_report_errp(errp); +| +- error_reportf_err(local_err, args); ++ error_reportf_errp(errp, args); +| +- warn_report_err(local_err); ++ warn_report_errp(errp); +| +- warn_reportf_err(local_err, args); ++ warn_reportf_errp(errp, args); +) +?- local_err = NULL; + +| +- error_propagate_prepend(errp, local_err, args); ++ error_prepend(errp, args); +| +- error_propagate(errp, local_err); +| +- &local_err ++ errp +) + ...> + } + +// Convert remaining local_err usage. For example, different kinds of +// error checking in if conditionals. We can't merge this into +// previous hunk, as this conflicts with other substitutions in it (at +// least with "- local_err = NULL"). +@ disable optional_qualifier@ +identifier rule1.fn, rule1.local_err; +symbol errp; +@@ + + fn(..., Error ** ____, ...) + { + <... +- local_err ++ *errp + ...> + } + +// Always use the same pattern for checking error +@ disable optional_qualifier@ +identifier rule1.fn; +symbol errp; +@@ + + fn(..., Error ** ____, ...) + { + <... +- *errp != NULL ++ *errp + ...> + } + +// Revert temporary ___ identifier. +@ disable optional_qualifier@ +identifier rule1.fn; +@@ + + fn(..., Error ** +- ____ ++ errp + , ...) + { + ... + } |